Problem: $ { \left[\begin{array}{rrr}{2} & {4} & {-1} \\ {0} & {-2} & {1}\end{array}\right]-\left[\begin{array}{rrr}{2} & {2} & {4} \\ {-2} & {2} & {-2}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rrr}{2}-{2} & {4}-{2} & {-1}-{4} \\ {0}-{-2} & {-2}-{2} & {1}-{-2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{0} & {2} & {-5} \\ {2} & {-4} & {3}\end{array}\right]}$